by Robert Sparks
A traveling worker hears a unique ringtone on his cell phone, checks the screen and finds a presence notification that a colleague is awaiting a plane in the same airport.
A soccer parents presence channel on a dads SIP softphone shows all the teams parents are available to share a group voice or IM session right now.
A teenager who just wrecked his moms car checks the family presence channel on his mobile phone to find out his mothers current mood.
These examples only hint at how presence technologies will enable a large class of services not achievable on existing mobile networks.
Presence technologies already have revolutionized how and when network-connected buddies communicate. A quick look at the instant messaging (IM) window on a PC tells which buddies are present and available to converse and which ones have stepped out or are otherwise engaged. In short, the availability of presence information puts the instant in instant messaging. Presence enables one to avoid the uncertain, delayed responses associated with non-instant email or voice messages. The IP network user wastes less time and effortnot to mention network capacityon attempts to communicate with absent interlocutors.